Ceramics containing lead, zirconium, titanium, and oxygen (PZT ceramics) offer a combination of mechanical and electrical properties which makes them the construction materials of choice for certain categories of electrical equipment. For example, PZT ceramics are employed as capacitors in resonant microwave filters where a high dielectric constant and a relatively durable, non-porous solid phase are required.
PZT ceramics are commonly prepared by mixing lead oxide, zirconium oxide, and titanium oxide in various proportions, sometimes with additional components, and calcining the mixture to induce a reaction which produces a solid solution. The solid produced may be subsequently ground to a powder, pressed into a desired shape, and subjected to a severe heat treatment known as sintering. Sintering removes microscopically small pores from between individual particles of the powder and, ideally, creates a singlephase polycrystalline material without voids which is mechanically durable and substantially homogeneous.
In practice, the small pores are not entirely removed by sintering and voidless polycrystalline phases are only approximated. Researchers currently attempt to increase the density of sintered PZT ceramics by reducing their porosity, and also seek ways of carrying out the sintering at lower temperatures. Additionally, because the grinding of PZT ceramic materials into powder form in preparation for sintering is cumbersome, PZT ceramics having softer particles at the end of the calcining step are desired.